The present proposal is designed to quantify axonal sprouting in the dorsal root and tract of Lissauer in the rat. After sprouting is quantified, the effects of age on sprouting will be determined. Rats are the experimental animal and the operative paradigms are the surviving root of Liu and Chambers and the chronic hemisection. Axons will be counted in the electron microscope which has the resolution necessary for both myelinated and unmyelinated fibers.